1. |
What
is a "Flashback" ? |
|
A
"Flashback" is the combustion of a flammable
mixture within the equipments used for handling of flammable
gases viz. Pipelines, Gas Regulators, Gas Mixing Devices,
cylinders, etc. A "Flashback" is a root
cause of backfire, which normally appears in a mixing
device. The backfire occurs due to excessive heat and
the presence of fuel and oxidizer in the mixing device.
The heat of compression at the point of use is sufficient
enough to cause a "Flashback" inside
the mixing device. The backfire can be considered as a
very tiny or a micro version for cause of an explosion.
In event of a backflow, the residual mixture is consumed
by the flame point in such a rapid speed that it might
create a condition of velocity of a shock wave, which
is the probable cause of eruption of a "Flashback".
|
2. |
What are the causes of a "Flashback" ? |
|
|
Leaks
in the gas Handling Systems. |
|
|
Failure
to purge the Gas Systems. |
|
|
Improper
pressure setting of Gases. |
|
|
Mishandling
of Gas Systems under use. |
| |
|
3. |
What is "Flashback Arrestor" ? |
|
A
"Flashback Arrestor" is a device, designed
to provide added safety in handling of flammable gases.
The device consists of a flash arrestor, which can take
care of flashes returning back to the source or a gas
cylinder.
|
4. |
Why use a "Flashback Arrestor" ? |
|
A
"Flashback Arrestor" will prevent a "Flashback"
traveling past the point of installation, which is able
to create havoc. The arresting element inside it quenches
the "Flashback" in major cases.
The arresting element is ruggedly made to withstand
many "Flashback". The additional safety
feature prevents reverse flow of gases.
|
5. |
Why alone a "Non- Return Valve" is not sufficient ? |
|
A
"Non Return Valve" will stop the gas traveling
back to the source, wherein the valve seat of the "Non
Return Valve" is fit enough to seal and pressure
differential is sufficient as essential. However a "Non
Return Valve" will not stop a "Flashback"
because it does not contain a very basic element, which
holds back the Flashes traveling back to the Source or Cylinder.
|
6. |
What are the two general classification of a Flashback Arrestor
? |
|
A
Flashback Arrestor can be classified in two categories |
|
|
Wet type Flashback Arrestor |
|
|
It is a device wherein the sealing is done by help
of wet media, normally
water used as media. |
|
|
Dry type Flashback Arrestor |
|
|
It
is a device wherein the sealing is done by a sintered
metal or any other means
other than employing a liquid to arrest the Flashes.
|
7. |
Which category of Flashback Arrestor is more widely used ?
Why ? |
|
Dry
type Flashback Arrestor is a most widely used in major applications
at
major installations because of the inherent design
advantage. |
|
|
Leakage
problems are minimized due to absence of wet media. |
|
|
Maintenance
is virtually nil. |
|
|
Easy
to install, handle & maintain. |
|
|
No
reaction with source gas. |
| |
|
8. |
What is detonation ? Why it is dangerous ? How to prevent
it ? |
|
A
Flash propagation through an unburnt gas at a rate that
is above the speed of sound is called Detonation.
It has a power to Explode Pipelines, Cylinders, Compressors
& equipment
etc. It is prevented by maintaining proper distance
between an Ignition source and a Flashback Arrestor, often
termed as the "Run
Up". At least at two location, Flashback
Arrestors are to be installed, namely End-of-line &
In-line for a individual gas line to reduce the possibility
of Detonation. |
